X-ray Vision is a mutation found in the abandoned complex. It allows you to see into people's inventories and into closed containers. Additionally, your ability to see through junk gets you +1 to medic, scavenge, and locksmith.
The skills are always nice, and the x-ray vision is useful for checking if people are carrying valuable junk. The success of your x-ray, and how much you are able to see of a person inventory depends on how much clothing they are wearing.
You have trouble seeing in the dark. A lot. With this you will need to wear night vision goggles at night or carry a light source as you will be blind else wise. One way to counteract this is to get the chud mutation.
No change in appearance.